(define (A x y)
    (cond ((= y 0) 0)
          ((= x 0) (* 2 y))
          ((= y 1) 2)
          (else (A (- x 1)
                    (A x (- y 1))))))

(define (f n) (A 0 n))

(define (g n) (A 1 n))

(define (h n) (A 2 n))